1. Field of the Invention
The present invention relates to a method for detecting a trench created in an integrated thin film solar cell using a compound semiconductor, such as a chalcopyrite compound, and an apparatus for detecting a trench created in a thin film solar cell used for the same.
Here, the chalcopyrite compound includes CIGSS (Cu(In, Ga)(Se, S)2) and CIS (CuInS2) in addition to CIGS (Cu(In, Ga)Se2).
2. Description of Related Art
Thin film solar cells, which use a compound semiconductor for a light absorbing layer, generally have an integration-type structure where a number of unit cells are connected in series on a substrate.
A conventional method for manufacturing a chalcopyrite compound-based integrated-type thin film solar cell is described below. FIGS. 5(a) to 5(c) are diagrams showing the manufacturing steps thereof.
First, as shown in FIG. 5(a), an Mo electrode layer 12, which becomes a lower electrode on the plus side, is layered on an insulating substrate 11 made of solder lime glass (SLG) or the like, and then, a trench S for separating a lower electrode is created through a scribing process.
After that, as shown in FIG. 5(b), a light absorbing layer 13 made of a compound semiconductor (CIS) thin film is layered on the Mo electrode layer 12, and on top of this, a buffer layer 14 made of a ZnS thin film or the like is layered for a heterojunction. This buffer layer 14 essentially forms a part of the light absorbing layer 13. Subsequently, a trench M1 for the inter-electrode contact that reaches the Mo electrode layer 12 is created through a scribing process in a location that is away from the trench S by a predetermined distance in the lateral direction so as to be parallel to the trench S.
Next, as shown in FIG. 5(c), a transparent electrode layer 15 is formed on the buffer layer 14 as an upper electrode made of a ZnO:Al thin film, and a trench M2 for separating an electrode that reaches the Mo electrode layer 12 below is created through a scribing process so as to be parallel to the trench M1.
In the above-described steps of manufacturing an integrated-type thin film solar cell, a laser scribing method using a laser beam, as disclosed in Patent Document 1, and a mechanical scribing method using a trench creating tool having a blade at the front, as disclosed in Patent Documents 2 and 3, for example, are used as the technology for creating a trench through scribing.